The Sinclair QL Forum

So looking back the two chips were TI and the replacement was Hitachi. But it does look as if I ringed the wrong chip in my first picture

Yes, I agree, it was possible down to timing, 74HCT seem to be the best as they have the right threshold voltages for the 1's and 0's. But 74HC work in most cases.

Hi Ruptor, Yes as already said the last two comments were extra to the RAM issue. As I do on all old British computers from the eighty's and early ninety's I put a simple PNP amp circuit, this gives a colour composite output on most machines, some need a bit more work or the signal inverting. Video ...

Hi Pr0f,

I have the JED files from Tetroid and was just waiting for him to give me the go ahead to share them, do you still require them?

Technical Chap

Hi Cristian, I have been following this thread for a while as I to have a QL which will not boot and gives a garbled screen, at first I replaced the decoder logic chips (74LS257's and LS245) and it made little difference. So, as you do sometimes, you put the computer away and start another project. ...